Reaction Steps
To an oven-dried flask, 1-boc-piperazine (3.19 g, 17.1 mmol), Cs2CO3 (5.82 g, 17.86 mmol), Pd2(dba)3 (1.44 g, 1.57 mmol), rac-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (0.89 g, 1.43 mmol), toluene (8 mL) and compound 14 (3.89 g, 14.26 mmol) were added. While stirring the reaction mixture at room temperature, the air in the flask was removed and replaced by N2. This process was repeated three times. The reaction temperature was brought to 110° C. and stirred for 8 h. Ethyl acetate (40 mL) was added to the mixture at room temperature, washed with H2O (15 mL), brine (10 mL), dried over Na2SO4 and evaporated. The brown oily material was chromatographed on a silica column, eluting with hexanes:ethyl acetate (3:7) and then changing to (1:1) to obtain the title compound 15 as light yellow solid (3.88 g, 72%). IR (KBr) νmax. cm−1: 3441 (NH), 3060 (Ar—H), 2963 (Alph-H), 1696 (C═O), 1607, 1577 (C═C), 1484, 1421 (NO2), 1243 (C—N), 1168 (C—O). 1H NMR (500 MHz, CDCl3) δ=1.49 (s, 9H, (C(CH3)3), 2.17 (s, 3H, CH3), 3.42 (br. s, 4H, 2CH2), 3.61 (br. s, 4H, 2CH2), 5.54 (s, 2H, CH2), 6.76 (dd, 1H, J=2.3, 9.3 Hz, H-6), 6.88 (br. s, 1H, H-2), 8.17 (d, 1H, J=9.4 Hz, H-5). 13C NMR (125.7 MHz, CDCl3) δ=20.93 (CH3), 28.39 (C(CH3)3), 46.82 (CH2), 50.02 (CH2), 66.12 (CH2), 80.42 (C(CH3)3), 112.30 (aromatic-C), 112.48 (aromatic-C), 128.17 (aromatic-C), 135.60 (aromatic-C), 137.03 (aromatic-C), 153.02 (aromatic-C), 154.56 (CO), 170.29 (CO). Calculated (%) for C18H26N4O5 (378.19); C, 57.13; H, 6.93; N, 14.81. found (%); C, 57.07; H, 6.99; N, 14.71.
